R Value

k Value

Perimeter of a round duct is

1

0.86

85% a rectangular duct

2

0.80

80% a rectangular duct

3

0.72

72% a rectangular duct

4

0.65

65% a rectangular duct

5

0.60

60% a rectangular duct

6

0.55

55% a rectangular duct

7

0.51

51% a rectangular duct

8

0.48

48% a rectangular duct